The prupose of the proposed research is to test the hypothesis that specificity of reflex influences on sympathetic efferent activity is partially as consequence of heterogeneity among spinal preganglionic neurons. Experiments will be performed in alpha chloralose anesthetized cats using standard electrophysiological techniques. Carotid sinus baroreceptor and cardiopulmonary afferent influences on preganlionic neurons innervating the heart, kidney and other viscera will be compared. Attempts will be made to ascertain the relative functional dedication of individual preganglionic neurons to specific organs. Preganglionic activity will be recorded within the spinal cord using microelectrodes. Computerized techniques such as correlation analysis, power spectral analysis and generation of histograms will be used to evaluate responses.